Apparatus to facilitate co-existence of bluetooth and wireless local area networks

ABSTRACT

A method for transmitting one or more first wireless local area network (WLAN) packets and one or more first Bluetooth (BT) packets. The method includes: prior to transmission of the one or more first wireless local area network (WLAN) packets, predicting a first time at which the transmission of the one or more first wireless local area network (WLAN) packets is going to end, and predicting a second time at which reception of one or more second Bluetooth (BT) packets is going to start; and simultaneously transmitting the one or more first wireless local area network (WLAN) packets and the one or more first Bluetooth (BT) packets in response to the first time being predicted to occur prior to the second time.

The present disclosure is a continuation of and claims priority to U.S.patent application Ser. No. 12/435,707, filed May 5, 2009, now U.S. Pat.No. 8,442,016, issued May 14, 2013, which is incorporated herein byreference.

TECHNICAL FIELD Background

Wireless Personal Area Networks (WPANs) have been increasingly gainingpopularity because of the flexibility and convenience these networksprovide. WPAN systems, such as those based on Bluetooth (BT) technology,may be used in a variety of peripheral devices, mobile terminals, etc.by providing short distance wireless links that allow connectivitywithin a short (e.g., 10 meters) range.

Wireless Local Area Networks (WLANs) have also been increasingly gainingpopularity for providing wireless connectivity to devices that arelocated within a relatively larger geographical area, such as the areacovered by a room, building, or a campus, for example. WLAN systems maybe based on, for example, Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 protocols, e.g., IEEE 802.11b protocol releasedon 1999, IEEE 802.11g protocol released on 2003, or any otherappropriate IEEE 802.11 protocol. A WLAN may have a range of 100 meters,and may be utilized to supplement the communication capacity provided bya wired Local Area Network (LAN).

In some instances, it may be desirable to operate a WLAN system inconjunction with a WPAN system to provide users with an enhanced overallfunctionality. However, co-existence of BT and WLAN may create severalchallenges. For example, both BT and WLAN radio devices may operate inthe 2.4 GHz (2.4000-2.4835 GHz) Industrial, Scientific, and Medical(ISM) unlicensed band, which may create several challenges forco-existence of BT and WLAN.

In other examples, a single device (e.g., a laptop, a cellular phone,etc.) may perform both WLAN and BT transactions. In such a situation notonly does the problem of potential interference arise, but also due atleast in part to the specifications (e.g., size and power consumption)of the device, WLAN and BT radio devices (e.g., transceivers) may berequired to share one or more common antennas and/or common front endprocessors, which may create additional challenges.

SUMMARY

In various embodiments, the present disclosure provides an apparatus anda method for coexistence of BT and WLAN. More specifically, there isprovided, in accordance with various embodiments of the presentinvention, an apparatus comprising an antenna configured tosimultaneously transmit wireless local area network (WLAN) packets andreceive Bluetooth (BT) packets, a WLAN transmission system configured toprocess WLAN packets before said transmission, and a BT reception systemconfigured to process the received BT packets. The apparatus may furthercomprise a power amplifier configured to amplify WLAN signal before saidtransmission, and a switch configured to selectively bypass the poweramplifier. The apparatus may further comprise a directional coupleroperatively coupled between the power amplifier and the antenna andconfigured to transmit WLAN signals from the WLAN transmission system tothe antenna, and further configured to transmit received BT signals fromthe antenna to the BT reception system.

In various embodiments, the antenna may be further configured tosimultaneously receive WLAN packets and BT packets. The apparatus mayfurther comprise a WLAN reception system configured to process thereceived WLAN packets. The antenna may be further configured tosimultaneously receive WLAN packets and transmit BT packets. Theapparatus may further comprise a directional coupler operatively coupledto the antenna and configured to transmit the received WLAN packets fromthe antenna to a WLAN reception system, and further configured totransmit the BT packets from a BT transmission system to the antenna. Invarious embodiments, the apparatus may further comprise a single poletriple throw (SP3T) switch configured to be operatively coupled to theantenna and to operate in any one of a plurality of positions, andfurther configured to enable simultaneous transmission of WLAN packetsand reception of BT packets while operating in a first position. Invarious embodiments, the SP3T may be further configured, while operatingin a second position, to enable simultaneous reception of WLAN packetsand BT packets. The SP3T may be further configured, while operating in athird position, to enable simultaneous reception of WLAN packets andtransmission of BT packets.

In various embodiments, there is also provided, in accordance withvarious embodiments of the present invention, an apparatus comprising anantenna configured to simultaneously transmit Bluetooth (BT) packets andreceive wireless local area network (WLAN) packets, a WLAN receptionsystem configured to process the received WLAN packets, and a BTtransmission system configured to process the BT packets before saidtransmission. The antenna may be further configured to simultaneouslyreceive BT packets and WLAN packets. The antenna may be furtherconfigured to simultaneously transmit WLAN packets and receive BTpackets.

In various embodiments, there is also provided, in accordance withvarious embodiments of the present invention, a method comprising firstpredicting, prior to transmitting one or more wireless local areanetwork (WLAN) packets, that the transmission of the one or more WLANpackets is going to end at a first time; second predicting, prior tosaid transmitting one or more WLAN packets, that a reception of a firstone or more Bluetooth (BT) packets is going to start at a second time;and transmitting the one or more WLAN packets while simultaneouslytransmitting a second one or more BT packets, if the first time occursprior to the second time. In various embodiments, said transmitting mayfurther comprise transmitting the WLAN packets while simultaneouslytransmitting the second one or more BT packets, if the transmission ofthe one or more WLAN packets is predicted to end prior to the start ofreception of the first one or more Bluetooth BT packets. The method mayfurther comprise avoiding transmission of the one or more WLAN packetsif the second time occurs prior to the first time, and/or issuing atransmission ending synchronization signal in response to ending thetransmission of the one or more WLAN packets and transmission of thesecond one or more BT packets.

In various embodiments, there is also provided, in accordance withvarious embodiments of the present invention, a method comprising firstpredicting, prior to receiving one or more wireless local area network(WLAN) packets, that the reception of the one or more WLAN packet isgoing to end at a first time; second predicting, prior to receiving theone or more WLAN packets, that a transmission of a first one or moreBluetooth (BT) packets is going to start at a second time; and receivingthe WLAN packets while simultaneously receiving a second one or more BTpackets, if the first time occurs prior to the second time. The methodmay further comprise transmitting the first one or more BT packets,starting from the second time, if the first time occurs prior to thesecond time, and/or avoiding transmission of the first one or more BTpackets from the second time if the second time occurs prior to thefirst time. The method may further comprise notifying, if the secondtime occurs prior to the first time, an access point to not transmit theone or more WLAN packets so as to avoid receiving the one or more WLANpackets before transmitting the first one or more BT packets.

In various embodiments, there is also provided, in accordance withvarious embodiments of the present invention, a method comprisingbeginning to receive a wireless local area network (WLAN) frame,detecting contents of a preamble of the WLAN frame, and predicting thatthe WLAN frame is a beacon frame based at least in part on saiddetecting. Said detecting may further comprise detecting contents of apreamble signature included in the preamble, wherein the preamblesignature includes an originating address, a destination address, and atype of the WLAN frame. The method may further comprise avoidingtransmission of one or more Bluetooth packets until the entire WLANframe is received.

In various embodiments, there is also provided, in accordance withvarious embodiments of the present invention, a method comprisingreceiving, from an access point, a wireless local area network (WLAN)frame, the wireless frame including a short preamble and/or a longpreamble, and transmitting to the access point, a second WLAN frame inresponse to said receiving, the transmitted second WLAN frame includingan orthogonal frequency-division multiplexing (OFDM) preamble. Themethod may further comprise transmitting a request to the access pointto utilize OFDM preamble in one or more future WLAN frames to betransmitted by the access point.

In various embodiments, there is also provided, in accordance withvarious embodiments of the present invention, a method comprisingreceiving one or more wireless local area network (WLAN) packets,predicting an end of reception of one or more BT packets at a firsttime, the BT packets being received simultaneously with the WLANpackets, predicting a second time to be a start time of a shortinterframe space (SIFS) acknowledgement that is configured toacknowledge the reception of the one or more WLAN frames, andtransmitting the short interframe space (SIFS) acknowledgement if thefirst time is predicted to occur prior to the second time. The methodmay further comprise transmitting an extended interframe space (EIFS)acknowledgement if the first time is predicted to occur subsequent tothe second time.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be readily understood by thefollowing detailed description in conjunction with the accompanyingdrawings. To facilitate this description, like reference numeralsdesignate like structural elements. Embodiments of the invention areillustrated by way of example and not by way of limitation in thefigures of the accompanying drawings.

FIG. 1 schematically illustrates an exemplary wireless system.

FIG. 2 schematically illustrates an exemplary front end processingsystem.

FIG. 3 schematically illustrates an exemplary front end processingsystem.

FIG. 4 schematically illustrates another exemplary front end processingsystem.

FIG. 5 schematically illustrates another exemplary front end processingsystem.

FIG. 6 schematically illustrates another exemplary front end processingsystem.

FIG. 7a illustrates an exemplary WLAN channel and a plurality of BTchannels utilizing random hopping.

FIG. 7b illustrates an exemplary WLAN channel and a plurality of BTchannels utilizing adaptive frequency hopping (AFH).

FIG. 8a illustrates an exemplary WLAN channel and a plurality of BTchannels utilizing adaptive hopping pattern control.

FIG. 8b illustrates a method for Bluetooth hopping pattern control.

FIG. 9 schematically illustrates an exemplary device that is capable ofsupporting BT communication.

FIG. 10 illustrates an exemplary method for recalibrating a secondaryclock of FIG. 9.

FIG. 11 illustrates an exemplary method for arbitration among BT andWLAN.

FIG. 12a schematically illustrates an exemplary timing diagram for BTand WLAN packet transmission and/or reception by a device of FIG. 1.

FIG. 12b illustrates an exemplary method for transmission endingsynchronization.

FIG. 13a illustrates an exemplary timing diagram for BT and WLAN packettransmission and/or reception by a device of FIG. 1.

FIG. 13b illustrates an exemplary method for reception endingsynchronization.

FIGS. 14a-14d illustrate exemplary methods for WLAN beacon reception.

FIG. 15 illustrates an exemplary method for WLAN data rate control.

FIG. 16 illustrates an exemplary method for WLAN preamble control.

FIGS. 17a and 17b illustrate exemplary timing diagrams for WLANacknowledgement timing control.

FIG. 17c illustrates an exemplary method for WLAN acknowledgement timingcontrol.

FIG. 18 is a block diagram of an exemplary system 1800 suitable for useto practice the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof wherein like numeralsdesignate like parts throughout, and in which is shown by way ofillustration embodiments in which the invention may be practiced. It isto be understood that other embodiments may be utilized and structuralor logical changes may be made without departing from the scope of thepresent invention. Therefore, the following detailed description is notto be taken in a limiting sense, and the scope of embodiments inaccordance with the present invention is defined by the appended claimsand their equivalents.

Various operations may be described as multiple discrete operations inturn, in a manner that may be helpful in understanding embodiments ofthe present invention; however, the order of description should not beconstrued to imply that these operations are order dependent.

The description may use the phrases “in an embodiment,” or “inembodiments,” which may each refer to one or more of the same ordifferent embodiments. The phrase “in some embodiments” is usedrepeatedly. The phrase generally does not refer to the same embodiments;however, it may. The terms “comprising,” “having,” and “including” aresynonymous, unless the context dictates otherwise. The phrase “A and/orB” means (A), (B), or (A and B). The phrase “A/B” means (A), (B), or (Aand B), similar to the phrase “A and/or B.” The phrase “at least one ofA, B and C” means (A), (B), (C), (A and B), (A and C), (B and C) or (A,B and C). The phrase “(A) B” means (B) or (A and B), that is, A isoptional.

FIG. 1 schematically illustrates an exemplary wireless system 10. Thesystem 10 includes a device 14 that is configured to wirelesslycommunicate with an access point AP 16 of a WLAN network. Thus, the AP16 and the device 14 may be a part of a WLAN, and may wirelesslycommunicate using an appropriate WLAN protocol (e.g., IEEE 802.11b, IEEE802.11g, etc.). The device 14 is configured to wirelessly communicatewith a BT enabled device 18 in accordance with a BT specification (e.g.,Bluetooth specification version 2.0 released on 2004, or any otherappropriate version of the BT specification). As will be readilyunderstood by those skilled in the art, the device 14 may alsocommunicate with other devices (not illustrated in FIG. 1) using WLAN,BT, and/or any other appropriate wired and/or wireless protocol.

The device 14 may be, for example, a laptop configured to communicatewith a BT enabled wireless keyboard (or a any other BT enabledperipheral like a mouse, a printer, a camera, a headphone, etc.) andwith the WLAN AP 16. The device 14 may be a cell phone configured tocommunicate with a BT enabled headphone and also with the AP 16.

Front End Processing

FIG. 2 schematically illustrates an exemplary front end processingsystem 200. The front end processing system 200 may be present in adevice (e.g., device 14 of FIG. 1) that may be configured to wirelesslycommunicate with a WLAN device (e.g., AP 16) using an appropriate WLANprotocol and a Bluetooth enabled device (e.g., device 18) using anappropriate Bluetooth specification.

The system 200 includes an antenna 204 configured to trans-receivewireless communication to and/or from the AP 16 and/or the BT enableddevice 18. Thus, the antenna 204 may be configured to transmit and/orreceive WLAN and/or BT frames and packets.

The system 200 also includes a single pole double throw (SPDT) switch208 operatively coupled to the antenna 204. The switch may be configuredto be either in position 212 or at position 214, as illustrated by thedotted lines in FIG. 2. When in position 212, the switch 208 operativelycouples the antenna 204 with a WLAN transmission (TX) and reception (RX)system 280, and the device 14 may transmit and/or receive WLAN packetsto and/or from AP 16 utilizing the antenna 204. When in position 214,the switch 208 operatively couples the antenna 204 with a BT TX and RXsystem 282, and the device 14 may transmit and/or receive BT packets toand/or from the BT enabled device 18 utilizing the antenna 204.

Thus, at any given time, the device 14 may be able to transmit and/orreceive either WLAN packets or BT packets, based at least in part on theposition of the switch 208. However, using the system 200, it may not bepossible to transmit and/or receive WLAN and BT packets simultaneously.

FIG. 3 schematically illustrates an exemplary front end processingsystem 300. The front end processing system 300 may be present in adevice (e.g., device 14 of FIG. 1) that may be configured to wirelesslycommunicate with a WLAN device (e.g., AP 16) using an appropriate WLANprotocol and a Bluetooth enabled device (e.g., device 18) using anappropriate Bluetooth specification.

The system 300 includes an antenna 304 coupled to a single pole triplethrow (SP3T) switch 308. The SP3T switch 308 may be configured to be inany one of three positions (312, 314 or 316) at any given time.

In various embodiments, when the SP3T switch 308 is at position 312, theantenna 304 is operatively coupled to a WLAN TX system 380 through theswitch 308 and through a power amplifier (PA) 320. In variousembodiments, a switch 328 may also be coupled to both ends of the poweramplifier 320 and may be configured to selectively bypass the PA 320,whenever required. For example, the PA 320 may be utilized to amplifyWLAN signals before transmission through the antenna 304. However, iflow power WLAN transmission is desired, the PA 320 may be bypassedutilizing switch 328.

In various embodiments, when the SP3T switch 308 is at position 314, theantenna 304 may be coupled to a WLAN RX and BT RX system 382 through theswitch 308 and through a low noise amplifier (LNA) 324, which may beutilized to amplify the received WLAN and/or BT signals, and/or reduce anoise figure of the receiver subsystems. Thus, when the switch 308 is atposition 314, the device 14 of FIG. 1 may receive WLAN packets and/or BTpackets through the antenna 304, from the AP 16 and/or the BT enableddevice 18, respectively. In various embodiments, the reception of theWLAN packets and the BT packets may be simultaneous, i.e., the front endprocessing system 300 may be configured to simultaneously receive WLANpackets and the BT packets. Once the WLAN and/or the BT packets arereceived at the WLAN RX and BT RX system 382, the packets may beprocessed using a WLAN and/or BT processing unit (not illustrated inFIG. 3), as is well known to those skilled in the art.

In various embodiments, when the SP3T switch 308 is at position 316, theantenna 304 may be operatively coupled to a BT TX system 384, and thedevice 14 may transmit BT packets to the BT enabled device 18 utilizingthe antenna 308.

Thus, in various embodiments, the front end processing system 300 may beconfigured to allow simultaneous reception of WLAN packets and the BTpackets (when switch 308 is at position 314), and also transmission ofWLAN packets (when switch 308 is at position 312) and BT packets (whenswitch 308 is at position 316).

As will be readily understood by those skilled in the art that theswitch 328, PA 320 and/or the LNAA 324 may be optional, and in variousembodiments, one or more of those components may not be present in thefront end processing system 300 (or any other front end processingsystem disclosed herein later).

FIG. 4 schematically illustrates an exemplary front end processingsystem 400. The front end processing system 400 may be present in adevice (e.g., device 14 of FIG. 1) that may be configured to wirelesslycommunicate with a WLAN device (e.g., AP 16) using an appropriate WLANprotocol and a Bluetooth enabled device (e.g., device 18) using anappropriate Bluetooth specification.

Similar to the front end processing system 300 of FIG. 3, in variousembodiments, the system 400 may include an antenna 404 coupled to a SP3Tswitch 408 that is configured to be in any one of three positions (412,414 or 416) at any given time. When the SP3T switch 408 is at position412, the antenna 404 may be coupled to a WLAN TX system 480 through theswitch 408 and a power amplifier 420. In various embodiments, a switch428 may be configured to selectively bypass the power amplifier 420,whenever required.

The system 400 also includes a SPDT switch 450 operatively coupled tothe SP3T switch 408 such that when the switch 408 is at position 414, aport of the SPDT switch 450 is operatively coupled to the antenna 404through the SP3T switch 408. The system 400 also includes a powerdivider or directional coupler 434 operatively coupled to the SP3Tswitch 408 such that when the switch 408 is at position 416, a port ofthe coupler 434 is operatively coupled to the antenna 404 through theSP3T switch 408. A second port of the coupler 434 is coupled to a portof the SPDT switch 450, and another port of the coupler 434 is coupledto a BT TX system 484. An output of the SPDT switch 450 is coupled to aWLAN RX and BT RX system 482, optionally through an LNA 424. In variousembodiments, the SPDT switch 450 may be configured to be, at any giventime, either in position 452 or in position 454, such that the SPDTswitch 450 operatively couples an output of the antenna 408 or an outputof the coupler 434 to the WLAN RX and BT RX system 482, respectively.

In various embodiments, whenever it is desirable to transmit WLANpackets, the WLAN TX system 480 may transmit the same (optionally afteramplification utilizing the PA 420) through the SP3T switch 408 (inposition 412) and the antenna 404.

When the SP3T switch is at position 414, the antenna may receive WLANpackets and/or BT packets (i.e., may receive WLAN packets and BT packetssimultaneously), and transmit the WLAN packets and/or BT packets to theWLAN RX and BT RX system 482 through SPDT switch 450 (operated at 452position) and LNA 424. Thus, the front end processing system 400 may beconfigured to simultaneously receive WLAN packets and BT packets.

When the SP3T switch is at position 416, the antenna 404 may beconfigured to transmit BT packets and/or receive WLAN packets. Forexample, while the SP3T switch is at position 416, the coupler 434 mayoperatively couple the BT TX system 484 to the antenna 404 throughswitch 408, thereby allowing BT packet transmission. In variousembodiments, the coupler may also be configured to receive WLAN packetsreceived by the antenna 404 and transmit the received WLAN packets tothe WLAN RX and BT RX system 482 through the SPDT switch 450 (operatedat position 454) and the LNA 454. Thus, the front end processing system400 may be configured to simultaneously transmit BT packets and receiveWLAN packets by appropriately configuring the SP3T switch 408 (inposition 416), SPDT switch 450 (in position 454), and the directionalcoupler 434.

FIG. 5 schematically illustrates an exemplary front end processingsystem 500. The system 500 of FIG. 5 may be at least in part similar tothe system 400 of FIG. 4, and the components of system 500 that aresimilar to that in the system 400 has been denoted by same referencecharacters in FIG. 5 as in FIG. 4.

For example, similar to the system 400 of FIG. 4, the system 500 of FIG.5 may include antenna 404, SP3T switch 408, PA 420, switch 428, WLAN TXsystem 480, WLAN RX and BT RX system 482, BT TX system 484, LNA 424,and/or coupler 434.

Instead of the SPDT switch 450 of FIG. 4, the system 500 includes a SP3Tswitch 550 (operating in position 556, 452 or 454), as illustrated inFIG. 5. Also, the system 500 includes a power divider or directionalcoupler 536 operatively coupled between the SP3T switch 408 and the PA420, a port of which may be operatively coupled to a port of the ST3Tswitch 550.

Referring again to FIG. 5, when the SP3T switch 408 is at position 412,the WLAN TX system 480 may transmit WLAN packets (to the AP 16, forexample) through the coupler 536, switch 408 and antenna 404 (possiblyafter amplification by the PA 420). At the same time (i.e., while switch408 is at position 412), the antenna 404 may receive BT packets (fromthe BT enabled device 18, for example) and transmit the received BTpackets to the WLAN RX and BT RX system 482 through the coupler 536,SP3T switch 550 (operating at position 556), and LNA 424. That is, byutilizing the front end system 500, it may be possible to transmit WLANpackets simultaneously with receiving BT packets.

In various embodiments, at any given time, if the front end processingsystem 500 is transmitting WLAN packets but not simultaneously receivingany BT packets, the device 14 may utilize the PA 420 to amplify the WLANsignals before such transmission occurs. However, if the front endprocessor 500 is transmitting WLAN packets simultaneously with receivingBT packets, the device 14 may bypass the PA 420 (by utilizing the switch428), i.e., not utilize the PA 520 to amplify the WLAN signals beforetransmission. That is, during simultaneous transmission of WLAN packetsand reception of BT packets, the transmission of WLAN packets may beperformed at relatively lower power to avoid possibilities ofinterference with the reception of the BT packets.

In various embodiments, the front end processing system 500 may alsosimultaneously receive BT and WLAN packets by configuring SP3T switch408 (at position 414), SP3T switch 550 (at position 452) and LNA 424, ashas been previously discussed herein with respect to FIG. 4.

In various embodiments, the front end processing system 500 may alsosimultaneously receive WLAN packets and transmit BT packets byconfiguring SP3T switch 408 (at position 416), coupler 434, SP3T switch550 (at position 454) and LNA 424, as has been previously discussedherein with respect to FIG. 4.

FIG. 6 schematically illustrates an exemplary front end processingsystem 600. The individual components of FIG. 6 are at least in partsimilar to those discussed with respect to FIGS. 3-5, and theinterconnection between the components in FIG. 6 will be apparent tothose skilled in the art based on the disclosure and teachings providedherein, and hence, a detailed description of the same is omitted herein.

In various embodiments, when the SP3T switch 608 is at position 612, theWLAN TX system 680 may transmit WLAN packets through PA 620 (orbypassing the PA 620 by utilizing switch 628 while operating in a lowWLAN transmission power mode). In various embodiments, when the SP3Tswitch 608 is at position 616, the BT TX and RX system 684 may transmitBT packets through SP3T switch 650 (operating in position 654) andantenna 604.

When the SP3T switch 608 is at position 614, the antenna 604 may receiveWLAN and BT packets. The WLAN RX system 682 may receive the WLAN packetsreceived by the antenna 604, through the LNA 624 and coupler 634. Invarious embodiments, the BT TX and BT RX system 684 may alsosimultaneously receive BT packets received by the antenna 604, throughthe LNA 624, coupler 634, and SP3T switch 650 (operating in position652). Thus, in various embodiments, it may be possible to simultaneouslyreceive BT and WLAN packets utilizing the system 600 of FIG. 6.

Bluetooth Hopping Pattern Control

WLANs (e.g., IEEE 802.11b/g) and Bluetooth usually utilize the same 2.4GHz ISM frequency band for communication, as is well known to thoseskilled in the art. Typically, in the allowed frequency band, a WLANsystem may utilize one or more 20 MHz channels. On the other hand,Bluetooth device may use 79 of the 83.5 available channels in the 2.4GHz band, hopping across these channels in a random (or pseudo-random)fashion and at a rate of, for example, 1600 times per second. FIG. 7aillustrates an exemplary WLAN channel and a plurality of BT channelsutilizing random hopping. Specifically, FIG. 7a illustrates one 20 MHzWLAN channel, and a plurality of BT channels. Although only about 12 BTchannels are illustrated in FIG. 7, there may be more BT channelsavailable. A conventional BT system may randomly hop across these BTchannels at regular interval, and an exemplary hopping pattern isillustrated by the curved lines with arrows in FIG. 7 a.

As illustrated in FIG. 7a , one or more of the BT channels may overlapwith the channel used by the WLAN. When BT is used in conjunction withWLAN (e.g., a single device employing both BT and WLAN mode ofcommunication), this overlapping may create interference andpossibilities of collision among BT and WLAN packets.

FIG. 7b illustrates an exemplary WLAN channel and a plurality of BTchannels utilizing adaptive frequency hopping (AFH). With AFH, a devicemay identify the channel utilized by WLAN, and avoid those BT channelsthat overlap with WLAN channel. For example, BT channels C, D, . . . , Gin FIG. 7b overlaps with the WLAN channel, and according to an AFHsystem, these BT channels may not be used for BT communication to reducechances of collision and interference among BT and WLAN packets.

In various embodiments, a device may also identify those BT channelsthat are near to the WLAN channel, and may decide to avoid these BTchannels as well. For example, BT channels A, B, H and J may be near tothe WLAN channel, and these BT channels may also not be used for BTcommunication to further reduce chances of collision and interferenceamong BT and WLAN packets. Thus, these BT channels may act similar to aguard band or avoidance region, and sufficiently separate the WLANchannels from the BT channels that are used for BT hopping.

In various embodiments, although AFH may reduce chances of collision andinterference among BT and WLAN packets, AFH may also reduce the numberof available channels used for BT communication by creating the guardband or avoidance region.

FIG. 8a illustrates an exemplary WLAN channel and a plurality of BTchannels utilizing adaptive hopping pattern control. Similar to an AFH,in FIG. 8a , those BT channels that overlap with the WLAN channel maynot be utilized for BT communication. However, in various embodiments,the BT channels that may be used as guard band channels in the avoidanceregion may be determined adaptively. That is, there may be some BTchannels (e.g., A, B, C and D) that may be close to the WLAN channel.However, the decision to use one or more of these BT channels for BTcommunication may be taken adaptively, based at least in part on, forexample, WLAN signal strength, BT signal strength, impact of adjacentchannel rejection, etc. For example, if the WLAN signal and/or the BTsignals are determined to be relatively weak, then the guard bandchannels or the avoidance region may be made relatively larger (e.g., byincluding channels A, B, H, and J in the guard band) to reduce possibleinterference to the WLAN signal. However, in other situations, it may bedesirable to use a shorter guard band or avoidance region, andaccordingly, for example, channels A and J may be used for BTcommunications (and possibly prohibiting BT channels B and H fromparticipating in BT communications and including these channels in theguard band or avoidance region).

FIG. 8b illustrates a method 850 for Bluetooth hopping pattern control.Referring to FIGS. 8a and 8b , the method 850 may include, at 854,identifying, by the device 14, a channel used by the device 14 and/orthe AP 16 for WLAN communications. At 858, a guard band or avoidanceregion around the WLAN channel may be adaptively determined by thedevice 14. At 862, the device 14 may develop a BT AFH pattern thatavoids BT channels that overlap with the WLAN channel and/or areincluded in the associated guard band or avoidance region.

Oscillator Calibration to Meet BT Low Power Operation (LPO) Requirement

FIG. 9 schematically illustrates an exemplary device 900 that is capableof supporting BT communication. For example, the device 900 of FIG. 9may be similar to the devices 14 and/or 18 of FIG. 1, and may be capableof transmitting and/or receiving BT packets. In various embodiments, theBT device 900 may operation in an active (or regular) mode, or in one ofseveral low power mode (e.g., sniff mode, hold mode, park mode, etc.),as is well known to those skilled in the art. In active mode, theaccuracy of clock signal required for the device 900 may be more thanthat required during a low power operation (LPO), as is also well knownto those skilled in the art. For example, while operating in the activemode, the device 900 may require a clock accuracy of at least 5-10parts-per-million (ppm), but while operating in a low power mode, thedevice 900 may require a clock accuracy of at least 250 ppm. Thus, theactive mode may require a relatively more accurate clock signal ascompared to the low power mode.

Referring again to FIG. 9, the device 900 includes a main clock 904(e.g., a system clock) and a secondary clock 908. In one embodiment, themain clock 908 has relatively more accuracy as compared to the secondaryclock 908, and also draws more power than the secondary clock 908. Thesecondary clock 908 may be, for example, an oscillator (e.g., a ringoscillator) that draws less current than the main clock 904. In variousembodiments, the main clock 908 may be utilized while the device 900 isoperating in the active mode. During a low power mode, the secondaryclock 908 may be used in lieu of the main clock for one or more BToperations of the device 900 to save power (as the secondary clock 908may draw less power than the main clock 904). That is, in the low powermode, the main clock 904 may be usually switched off to save power.

However, in various embodiments, the secondary clock 908 may not havethe clock accuracy (e.g., 250 ppm accuracy) required for low power BToperation. Accordingly, during a low power operation, it may bedesirable to periodically calibrate the secondary clock 908 such thatthe secondary clock 908 meets the BT low power operation clock signalrequirement.

As is well known to those skilled in the art, variations in process,voltage and temperature (PVT) may be responsible, at least in part, forinaccuracies in an oscillator clock signal. Thus, in variousembodiments, it may be desirable to reduce the PVT variations of thesecondary clock 908 so that the secondary clock signals meet theaccuracy requirement of the low power operation of the device 900.

The process variation of the secondary clock 908 may occur during themanufacturing of the secondary clock 908, and may not considerablychange once the secondary clock 908 has been manufactured. Thus, thesecondary clock 908 may be calibrated using a relatively more accurateclock (e.g., the main clock 904) to counter or reduce process relatederrors in the secondary clock 908. In various embodiments, thecalibration of the secondary clock 908 may be performed using, forexample, a calibration unit 920 included in the device 900.

In various embodiments, the clock signal of the secondary clock 908 maydrift with changes in the clock temperature, as is well known in theart. For example, there may be a drift of up to 500 ppm/° C. Such driftof clock signal with a change in the device temperature may be modeledand stored as clock drift vs. temperature model 916 in an appropriatememory location in the device 900. In various embodiments, the device900 may include a temperature sensor 912. It may be desirable toperiodically recalibrate the secondary clock 908 to remove or reduce theeffects of temperature variation.

While operating in low power mode, the BT operations of the device 900may be clocked by the secondary clock 908, and the main clock 904 may beusually switched off. In various embodiments, the calibration unit 920may periodically (e.g., every 500 millisecond (ms)) receive the device900's temperature from the temperature sensor 912. If the calibrationunit 920 notices significant differences in the current temperature fromthe last temperature reading, the calibration unit 920 may infer thatthe secondary clock 908 needs a recalibration because of possibletemperature drift. In various embodiments, the calibration unit 920 may,based at least in part on the clock drift vs. temperature model 916,decide the amount of recalibration required in the secondary clock 908to counter the temperature changes. In various embodiments, thecalibration unit 920 may also wake up the main clock 904 for a shortduration (e.g., 5 ms) and recalibrate the secondary clock 908 utilizingthe main clock 904. Recalibration of a clock is well known to thoseskilled in the art, and hence, will not be discussed in detail herein.

As is well known to those skilled in the art, variation in a voltageapplied to the secondary clock 908 may also result in variation in theassociated clock signal. In various embodiments, a voltage controlcircuit (not illustrated in FIG. 9) may ensure minimal variation involtage supplied to the secondary clock 908, to avoid any drift in thesecondary clock signal due to voltage variation. In various embodiments,the device 900 may include a voltage sensor (not illustrated in FIG. 9),which may measure any variation in the secondary clock voltage. In caseany significant voltage variation is observed, recalibration of thesecondary clock 908 may be performed.

FIG. 10 illustrates an exemplary method 1000 for recalibrating thesecondary clock 908 of FIG. 9. Referring to FIGS. 9 and 10, at 1004, thesecondary clock 908 may be calibrated to reduce or eliminate any processrelated variation. The calibration at 1004 may be performed, forexample, any time after the manufacturing the secondary clock 908 (e.g.,immediately after manufacturing the secondary clock 908, afterinstalling the secondary clock 908 in device 900, each time the device900 is restarted, etc.).

At 1008, the device 900 may enter a low power mode for a variety ofreasons well known to those skilled in the art. Upon entering the lowpower mode, the main clock 904 may be sent to sleep (i.e., disabled orturned off), and one or more BT components in the device 900 may beclocked by the secondary clock 908. At 1012, the temperature sensor 912may measure the temperature of one or more components of the device 900.At 1016, the calibration unit 920 may determine a difference between thecurrent and a previous reading of the temperature sensor 912, andcompare the difference with a threshold temperature level. If thedifference exceeds the threshold, at 1020, the main clock 904 may bewoken up from sleep mode (i.e., enabled or turned on), and thecalibration unit 920 may recalibrate the secondary clock 908 utilizingthe main clock 904 and/or the clock drift vs. temperature model 916, andthe main clock 904 may be re-sent to the sleep mode (i.e., disabled orturned off) upon successful recalibration. In case the difference doesnot exceed the threshold at 1016, the recalibration operation at 1020may be bypassed.

At 1024, a determination may be made if the device 900 needs to exit thelow power mode, and if so, the device 900 may exit the low power mode(to enter, for example, an active mode), thereby ending the method ofFIG. 10. If the device 900 continues to remain in the low power mode,the temperature sensor 912 may continue, at 1012, to periodicallymeasure the device 900's temperature.

Arbitration

In case of co-existence of BT and WLAN, the two different networks mayshare various resources (e.g., front end processing system, antenna,medium, etc.). For both BT and WLAN to operate satisfactorily in such aco-existence environment, it may be necessary to arbitrate access to oneor more shared resources between the two (BT and WLAN) networks. Severalarbitration schemes are well known to those skilled in the art (e.g.,packet traffic arbitration (PTA)) that may provide collaboration betweenBluetooth and WLAN up to a certain degree.

Some of the known arbitration schemes may be based on packets andtransactions. For example, during an arbitration scheme, a BT circuitryand a WLAN circuitry (included in, for example, device 14 of FIG. 1) maynegotiate which of the packets (BT or WLA) may be currently transmitted,and based upon this negotiation, the BT and/or the WLAN may be providedtime slots to transmit respective packets.

In various embodiments, it may be desirable to incorporate an importanceof the BT and/or WLAN packets, along with an importance of BT and WLANtransfers while performing the arbitration process. For example, a WLANtransfer may be associated with transmitting a plurality of WLANpackets. That is, a plurality of WLAN packets may be clubbed together(based, for example, on the type or association of the packets) as asingle transfer, and it may be desirable (if possible) to transmit theentire WLAN transfer without any interruption (caused, for example, bytransmission of BT packets).

FIG. 11 illustrates an exemplary method 1100 for arbitration among BTand WLAN. The method 1100 may include, at 1104, assigning priorities ofBT and/or WLAN packets and priorities of associated transfers. Forexample, a priority of a transfer that is to be started may be different(e.g., relatively lower) than a transfer that has always been started.Thus, if a WLAN transfer (comprising transferring plurality of WLANpackets associated with the single transfer) has already started, if maybe desirable to complete the transfer before starting a BT transfer.Accordingly, the current WLAN transfer may be assigned a higher priorityas compared to BT transfer. At the least, assignment of priority at 1104may be based at least in part on the knowledge, if available, of BTand/or WLAN transfers that are currently being undertaken. At 1108, anarbitration process may be performed based at least in part on thepriority assigned at 1104.

Transmission Ending Synchronization

In various embodiments, one or more of the front end processing systems(e.g., those previously discussed herein with reference to FIGS. 3-6)may allow certain degree to simultaneous BT and WLAN operations. Forexample, in various embodiments, a front end processing system may allowsimultaneous transmission of BT and WLAN packets (i.e., simultaneous BTTX and WLAN TX), and may also allow simultaneous reception of BT andWLAN packets (i.e., simultaneous BT RX and WLAN RX). The front endprocessing system may also allow simultaneous transmission of BT packetsand reception of WLAN packets (i.e., simultaneous BT TX and WLAN RX),and may also allow simultaneous reception of BT packets and transmissionof WLAN packets (i.e., simultaneous BT RX and WLAN TX).

In various embodiments, during certain links conditions, simultaneous(BT TX and WLAN RX) and simultaneous (BT RX and WLAN TX) may createinterference among BT and WLAN signals. However, in some of these linkconditions, simultaneous (BT TX and WLAN TX) and simultaneous (BT RX andWLAN RX) may not create any such interference (or create relativelylower interference).

Accordingly, it may be desirable to simultaneously perform (BT TX andWLAN TX) and/or also simultaneously perform (BT RX and WLAN RX), but notsimultaneously perform (BT TX and WLAN RX) and/or not simultaneouslyperform (BT RX and WLAN TX).

Thus, if BT and WLAN packets are simultaneously transmitted, it may bedesirable to end transmission of both BT and WLAN packets beforestarting reception of BT and/or WLAN packets. Similarly, if BT and WLANpackets are simultaneously received, it may be desirable to endreception of both BT and WLAN packets before starting transmission of BTand/or WLAN packets.

FIG. 12a schematically illustrates an exemplary timing diagram for BTand WLAN packet transmission and/or reception by the device 14 ofFIG. 1. Referring to FIG. 12a , BT packets may be transmitted betweentime t1 and t2, and BT packets may be scheduled to be received from timet4 onwards. Also, transmission of WLAN packets may start at time to.

In various embodiments, device 14 may predict (based in part, forexample, the assignment of BT slots), at or before time t0, that thenext BT reception is scheduled to start at or near time t4. Also, at orbefore time t0, the device 14 may predict (based in part, for example,on WLAN transmission and/or reception rate and/or WLAN payload) how longthe next WLAN transmission is going to last (i.e., may predict when thenext WLAN transmission would end).

As previously discussed, it may be desirable to avoid simultaneous BTreception and WLAN transmission. Thus, in various embodiments, at timet0, if it is predicted that the WLAN transmission is going to end (attime t3) before the scheduled start of the BT reception (at time t4),only then the WLAN packets may be transmitted from time t0. However, if,at or before time t0, if it is predicted that the WLAN transmission isgoing to end after the start of the next BT reception, then the WLANtransmission may not be started at all from time t0. This may avoidsituations where BT packets are received simultaneously withtransmitting WLAN packets.

In various embodiments, the end of the BT transmission and WLANtransmission may be marked with a transmission ending synchronizationsignal. Thus, the prediction and selective transmission of the WLANpacket from time t0 may ensure that the transmission endingsynchronization occurs before a BT reception.

FIG. 12b illustrates an exemplary method 1250 for transmission endingsynchronization. Referring to FIGS. 12a and 12b , the method 1250 mayinclude, at 1254, predicting, at or before time t0, when the next WLANtransmission is going to end. For example, referring to FIG. 12a , thedevice 14 may predict that the next WLAN transmission is going to end ator around time t3. At 1258, the device 14 may, at or before time t0,predict when the next BT and/or WLAN reception is going to begin. Forexample, referring to FIG. 12a , the device 14 may predict that the nextBT and WLAN reception is going to begin at least after time t4. As BTpackets are transmitted in slots, it may be possible to perform suchprediction based on, for example, the assignment of the BT slots.

At 1262, the WLAN transmission may be started from time t0 (possiblysimultaneously with BT transmission from time t1 to t2), if it isdetermined that the predicted end of WLAN transmission (i.e., time t3)is predicted to occur before the predicted beginning of BT and/or WLANreception (i.e., at time t4). This may ensure that the transmissionending synchronization (later of time t2 and t3) occurs before receptionof next BT and/or WLAN packets.

Although FIG. 12a illustrates both the BT reception and the WLANreception and/or handshake starting at time t4, this may not necessarilythe case, as will be readily understood by those skilled in the art. Forexample, in various embodiments, the BT reception and the WLAN receptionand/or handshake may start at different time; however, method 1250 mayensure the transmission ending synchronization occurs before the earlierof the BT reception and WLAN reception.

Reception Ending Synchronization

FIG. 13a illustrates an exemplary timing diagram for BT and WLAN packettransmission and/or reception by the device 14 of FIG. 1. Referring toFIG. 13a , BT packets may be received between time t1 and t2, and BTpackets may be scheduled for transmission from time t4 onwards. Also,reception of WLAN packets may start at time t0. In various embodiments,device 14 may predict (based in part, for example, on BT slotassignment), at or before time t0, that the BT transmission may start ator near time t4. Also, at or before time t0, the device may predict howlong the next WLAN reception is going to last (i.e., may predict whenthe next WLAN reception would end). For example, the device 14 maytransmit a power save (PS) poll to the WLAN AP 16, and the responsereceived from the AP 16 may include indication of how long the nexttransmission from AP 16 (i.e., WLAN RX at device 14) may last. As willbe readily understood by those skilled in the art based on thedisclosure and teachings provided herein, the PS poll and the responsemay be transmitted and received, respectively, by the device 14 prior totime t0. The prediction of WLAN RX ending period may also be based, forexample, in part of WLAN data rate, payload, etc.

As previously discussed, it may be desirable to avoid simultaneous BTtransmission and WLAN reception. Thus, in various embodiments, at timet0, if it is predicted that the WLAN reception is going to end (at timet3) before the start of the next BT transmission (from time t4), thenthe WLAN packets may be received from time t0. However, if, at time t0,if it is predicted that the WLAN reception is going to end after thestart of the next BT transmission, then the WLAN reception may not bestarted. For example, in that case, the device 14 may request the AP 16to not transmit WLAN packets (e.g., by transmitting a busy or sleepsignal to the AP 16).

Alternatively, if, at time t0, if it is predicted that the WLANreception is going to end after the start of the next BT transmission,then the next BT transmission may be delayed or cancelled to avoidsimultaneous WLAN reception and BT transmission.

FIG. 13b illustrates an exemplary method 1350 for reception endingsynchronization. Referring to FIGS. 13a and 13b , the method 1350 mayinclude, at 1354, predicting, at or before time t0, when the next WLANreception is going to end. For example, referring to FIG. 13a , thedevice 14 may predict that the next WLAN reception is going to end at oraround time t3. At 1358, the device 14 may, at or before time t0,predict when the next BT transmission is going to begin. For example,referring to FIG. 13a , the device 14 may predict that the next BTreception is going to begin at least after time t4.

The method 1350 may include, at 1362, determining if the predicted endof WLAN reception will occur before the predicted beginning of BTtransmission. If the determination is positive, at 1366, WLAN receptionmay be started from time t0, possibly simultaneously with BT reception.If the determination at 1362 is negative, at 1370, the device 14 mayrequest the AP 16 to not transmit the WLAN packets (so that the device14 does not receive any WLAN packets) and/or the device 14 may nottransmit the BT packets from time t4.

Speculative Reception of WLAN Beacon

A WLAN access point (e.g., AP 16 of FIG. 1) may periodically transmitbeacons that may include management frames, as is well known to thoseskilled in the art. The beacons and the included management frames maybe used for managing various WLAN activities, and for successfuloperation of the WLAN, it may be desirable that the device 14 receivethe beacon frames.

Because of the coexistence of BT and WLAN, there may be interferencebetween the two network and collision of BT and WLAN packets, due towhich one or more beacons may be lost (i.e., not received by the device14). In such circumstances, in various embodiments, the device 14 maytransmit a probe request to the AP 16 and receive a probe response fromthe AP 16, from which the device 14 may retrieve required beaconinformation. It may be advantageous to transmit and receive proberequest and probe response, respectively, at a higher data rate, ascommunication (i.e., transmission and/or reception) of WLAN packets at ahigher rate may reduce chances of collision of one or more WLAN packetswith the BT packets, as will be discussed in more detail herein later.

FIG. 14a illustrates an exemplary method 1400 for WLAN beacon reception.In various embodiments, the AP 16 may transmit beacons at regularinterval, and the device 14 may be aware of when the device 14 mayexpect to receive a beacon from the AP 16. For example, at 1404, device14 may predict that the AP 16 may transmit beacons at time t1 (and alsoat time t1+T, t1+2T, . . . , t1+nT, i.e., receive beacon periodicallyafter every T ms). Based on this prediction, the device 14 may block BTtransmission from time t1 to time (t1+x) (where x (2-10 micro second,for example) may be the maximum delay the beacon may experience to reachthe device 14) so that no BT packets are transmitted by the device 14while a WLAN beacon is expected by the device 14. As will be readilyunderstood by those skilled in the art based on the disclosure andteachings provided herein, if the beacon is received by device 14 beforethe end of the time (t1+x), the device 14 may start transmitting BTpackets instead of waiting until time (t1+x), if necessary.

A WLAN frame received by the device 14 from the AP 16 may includevarious fields, including a WLAN frame preamble field that may beincluded at the beginning portion of the frame, followed by a machineaddress code (MAC) header, and one or more other fields, as is wellknown to those skilled in the art. In various embodiments, the device 14may detect a WLAN frame preamble of a WLAN frame which is being receivedby the device 14. Based on the detection of the WLAN frame preamble, thedevice 14 may infer that the WLAN frame is a beacon frame, andaccordingly, block all BT transmissions until the full WLAN frame isreceived. This may avoid any possible interference between the receptionof the remaining portion of the WLAN frame and any potential BTtransmission. FIG. 14b illustrates another exemplary method 1420 forWLAN beacon reception. At 1424, the device 14 starts receiving a WLANframe, and from the WLAN frame preamble, predict that the WLAN frame isa beacon frame. At 1428, the device 14 may block BT TX transmissionuntil the whole WLAN frame has been received.

In various embodiments, the prediction at 1424, based only on the WLANframe preamble, may sometimes be erroneous as, for example, the WLANframe may be transmitted by an access point of another network (i.e.,not the WLAN network to which the device 14 belongs to) and/or may befor any other purpose, resulting in false detection.

FIG. 14c illustrates another exemplary method 1440 for WLAN beaconreception. The method 1440 includes, at 1444, starting to receive a WLANframe, and from the WLAN frame preamble and MAC header, predict that theWLAN frame is a beacon frame. Thus, unlike the method 1420 of FIG. 14b ,the method 1440 may wait until it receives and detects the MAC header(which includes the transmitting AP and destination address) of the WLANframe to predict that the WLAN frame may be a beacon frame. At 1448, thedevice 14 may block BT TX transmission until the whole WLAN frame hasbeen received. In various embodiments, using the MAC header for theprediction may result is less error and false detection. But the MACheader may be transmitted after the WLAN frame preamble, and waiting forthe MAC header may delay the prediction, thereby increasing chances ofalready starting the BT transmission before the prediction at 1444.

In various embodiments, a preamble signature may be included inpreambles of WLAN frames transmitted by the AP 16. The preamblesignature may include, among other information, the transmitting AP'saddress and/or the destination address of the WLAN frame, and/or otheridentification information. In various embodiments, the device 14 may besure, after detecting the preamble signature, that the WLAN frame is abeacon frame, is transmitted by the AP 16, and is intended for thedevice 14.

FIG. 14d illustrates another exemplary method 1460 for WLAN beaconreception. The method 1460 may include, at 1464, starting to receive aWLAN frame including a preamble signature in the frame preamble, andfrom the WLAN preamble signature, predict that the WLAN frame is abeacon frame. At 1468, the device 14 may block BT TX transmission untilthe whole WLAN frame has been received.

WLAN Rate Adaptation

In a conventional WLAN system (that is, when WLAN does not coexists withBT), a high frame error rate may imply, among other things, that thedata transmission rate may be too high, and it sometimes may beadvantageous to reduce the data rate. However, in various embodiments,in a BT/WLAN coexistence scenario, high frame error rate may be notbecause of high rate of transmission, but may be because of interferencecorruption due to BT-WLAN coexistence issues. In these scenarios,reducing the WLAN transmission rate may, instead of solving the problem,end in collision between the WLAN packets and BT packets because of arelatively low WLAN data transmission rate (as low WLAN data rate mayresult in the WLAN using the medium for a longer period, therebyincreasing chances of collision with BT packets).

In various embodiments, it may be desirable to transmit WLAN packets ata rate at least higher than a threshold rate (henceforth referred hereinas bottom rate). Ensuring the WLAN data rate is at least higher than thebottom rate may result in less collision between BT and WLAN packets (asWLAN may use the medium for relatively lesser time, thereby providingrelatively more time to BT to use the medium).

In various embodiments, the bottom rate may be determined adaptively,and may depend on a number of factors, including signal to noise ratio(SNR) of WLAN signals, transmission power, path loss, etc. In variousembodiments, a pilot frame (with minimal or no payload, i.e., minimal orno data) may be transmitted by the AP 16 and/or the device 14, and thebottom rate may be based, at least in part, on the signal quality of thereceived pilot frame. Bottom rate adaptation may also be performed bytransmitting for a short duration using various data rates, and theminimum transmission rate that produces satisfactory result may be usedas the bottom rate. Other ways of determining the bottom rate may bealso envisioned by those skilled in the art based on the disclosure andteachings provided herein.

FIG. 15 illustrates an exemplary method 1500 for WLAN data rate control.In various embodiments, the method 1500 may include, at 1504, adaptivelydetermining by the device 14 and/or access point 16 a bottom rate forWLAN data transmission. At 1508, the method may include transmittingWLAN packets with a data rate that is at least equal or higher than thedetermined bottom rate.

WLAN Preamble Control

A WLAN frame may have various types of preamble fields, e.g., a longpreamble field, a short preamble field, and/or an orthogonalfrequency-division multiplexing (OFDM) preamble field. One or more ofthese preamble fields may be utilized for WLAN communication based onseveral factors, including a type of the network, data transfer rate,etc. In various embodiments, a long preamble may be at least 192 microsecond (μsec) long, and short and OFDM preambles may be 96 μsec and 20μsec long, respectively. As previously discussed herein, in variousembodiments, it may be desirable to increase the WLAN data rate, andaccordingly, it may be desirable to use OFDM preamble instead of longpreamble and short preamble (if link conditions is favorable to do so),as OFDM preamble may have significantly shorter duration as compared toa long or a short preamble.

FIG. 16 illustrates an exemplary method 1600 for WLAN preamble control.Method 1600 may include, at 1604, receiving WLAN frames, by device 14,including a long and/or short preamble. At 1608, the device 14 maytransmit a WLAN frame to the AP 16 that may include an OFDM preambleand/or may also include information that may encourage or request the AP16 to utilize OFDM preamble in one or more future WLAN frames. Thus, themethod 1600 may encourage the AP 16 to adapt the OFDM preamble, therebydecreasing the air time utilized by WLAN packets, and decreasing chancesof collision of WLAN and BT packets.

WLAN Acknowledge Timing Control

In various embodiments, once the device 14 of FIG. 1 receives one ormore WLAN frames from the AP 16, the device 14 may transmit anacknowledgement frame to the AP 16. There may be several ways oftransmitting an acknowledgement frame based, for example, on the timegap between the end of receiving the one or more WLAN frames and startof the acknowledge frame. For example, a short interframe space (SIFS)acknowledgement frame may have relatively less gap between the end ofreceiving the one or more WLAN frames and start of the acknowledgeframe; whereas an extended interfame space (EIFS) may have relativelymore gap between the end of receiving the one or more WLAN frames andstart of the acknowledge frame.

As previously discussed herein, under certain link conditions, it may bedesirable to simultaneously receive BT and WLAN packets, but may not bedesirable to simultaneously receive BT packet and transmit WLAN packet.

Accordingly, it may be possible to simultaneously receive BT and WLANpackets. However, once the WLAN packets are received, it may bedesirable to transmit the WLAN acknowledgement frame only after the BTreception ends. However, if a SIFS acknowledgement is transmitted, theacknowledgement transmission may, in certain scenarios, start before theend of the BT reception. In these scenarios, it may be desirable totransmit a EIFS acknowledgement (instead of a SIFS acknowledgement) sothat the acknowledgement transmission is delayed and starts after theend of the BT reception

FIGS. 17a and 17b illustrate exemplary timing diagrams for WLANacknowledgement timing control, and FIG. 17c illustrates an exemplarymethod 1750 for WLAN acknowledgement timing control.

Referring to FIGS. 17a-17c , the method 1750 may include, at 1754,receiving a WLAN frame simultaneously with a BT frame. At 1758, themethod may include determining if a SIFS acknowledgement may overlapwith BT reception. For example, for the scenario illustrated in FIG. 17a, the BT reception ends before the end of the WLAN reception, and inthis case, it may be determined that a SIFS acknowledgement will notoverlap with any BT reception. On the other hand, for the scenarioillustrated in FIG. 17b , the BT reception may end after the end of theWLAN reception, and in this case, it may be determined that a SIFSacknowledgement may overlap with the BT reception.

Based at least in part on the determination made at 1758, the device 14may transmit, at 1762, either a SIFS acknowledgement (as in FIG. 17a )or an EIFS acknowledgement (as in FIG. 17b ).

In various embodiments, for some APs, a WLAN acknowledgement frame ACKmay be transmitted at higher rate or at a different modulation mode tominimize an air time used for communicating the acknowledgement, therebyreducing chances of collision with BT communication.

BT Friendly WLAN AP Association

In various embodiments, the device 14 of FIG. 1 may have access to morethan one WLANs, each having an associated AP (including, for example,access point 16). For example, a Wi-Fi hotspot may offer connectively tomore than one WLANs, each from a different broadband service provider.In various embodiments, the device 14 may select a WLAN and anassociated AP that is more BT friendly (i.e., a WLAN and an AP thatprovides relatively better support for WLAN-BT coexistence). Forexample, the device 14 may select a WLAN that offers better linkquality, higher data rate (that may reduce probability of collisionbetween WLAN packets and BT packets), etc. In various embodiments, thedevice 14 may select a WLAN such that an AP may not be too close to theBT enabled device 18 and/or device 14 to interfere with BTcommunications, etc. In other examples, in various embodiments, thedevice 14 may be aware of the BT hopping pattern, and may select a WLANthat offers WLAN channels that minimally use the BT hopping channels. Invarious embodiments, the device 14 may also periodically scan the mediumto identify if any new WLAN network is available that is also BTfriendly.

Exemplary Computing System

FIG. 18 is a block diagram of an exemplary system 1800 suitable for useto practice the present invention. As illustrated, system 1800 includesone or more processors or processor cores 1802, and system memory 1804.For the purpose of this application, including the claims, the terms“processor” and “processor cores” may be considered synonymous, unlessthe context clearly requires otherwise. Additionally, system 1800 mayinclude one or more mass storage devices 1806 (such as diskette, harddrive, compact disc read only memory (CDROM) and so forth), input/outputdevices 1808 and communication interfaces 1810 (such as networkinterface cards, modems and so forth). The elements of FIG. 18 may becoupled to each other via system bus 1812, which may represent one ormore buses. In the case of multiple buses, they may be bridged by one ormore bus bridges (not illustrated).

Each of these elements performs its conventional functions known in theart. In particular, system memory 1804 and mass storage 1806 may beemployed to store a working copy and a permanent copy of the programminginstructions implementing all or a portion of earlier describedfunctions, herein collectively denoted as 1822. The instructions 1822may be assembler instructions supported by processor(s) 1802 orinstructions that can be compiled from high level languages, such as C.

The permanent copy of the programming instructions may be placed intopermanent storage 1806 in the factory, or in the field, through, forexample, a distribution medium (not shown), such as a compact disc (CD),or through communication interface 1810 (from a distribution server (notshown)). That is, one or more distribution media having instructions1822 may be employed to distribute the instructions 1822 and programvarious client devices. The constitution of these elements 1802-1812 aregenerally well known, and accordingly will not be further described.

In various embodiments, the system 1800 may be configured to operate asdevice 14 of FIG. 1 and may communicate with a WLAN AP (e.g., AP 16) anda BT enabled device (e.g., device 18), using an appropriate WLANprotocol and BT specification, respectively. The system 1800 may alsoinclude an appropriate front end processing system (including anantenna), as illustrated in any one of FIGS. 3-7. In variousembodiments, the system 1800 may be configured to operate in a WLAN-BTcoexistence environment, and may be configured to practice one or moreof the embodiments previously described herein.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the art andothers, that a wide variety of alternate and/or equivalentimplementations may be substituted for the specific embodimentillustrated and described without departing from the scope of thepresent invention. This present invention covers all methods, apparatus,and articles of manufacture fairly falling within the scope of theappended claims either literally or under the doctrine of equivalents.For example, although the above discloses example systems including,among other components, software or firmware executed on hardware, itshould be noted that such systems are merely illustrative and should notbe considered as limiting. In particular, it is contemplated that any orall of the disclosed hardware, software, and/or firmware componentscould be embodied exclusively in hardware, exclusively in software,exclusively in firmware or in some combination of hardware, software,and/or firmware. This application is intended to cover any adaptationsor variations of the embodiment discussed herein. Therefore, it ismanifested and intended that the invention be limited only by the claimsand the equivalents thereof.

What is claimed is:
 1. An apparatus for receiving wireless local areanetwork packets and Bluetooth packets, wherein the apparatus comprises:means for predicting, prior to receiving a wireless local area networkpacket, (i) a first time at which reception of the wireless local areanetwork packet is going to end, and (ii) a second time at which atransmission of a first Bluetooth packet is going to start; and meansfor simultaneously receiving both the wireless local area network packetand a second Bluetooth packet in response to the first time beingpredicted to occur prior to the second time, wherein the first Bluetoothpacket is to be transmitted subsequent to the second Bluetooth packetbeing received.
 2. The apparatus of claim 1, wherein the apparatusfurther comprises: means for transmitting, in response to the first timebeing predicted to occur prior to the second time, the first Bluetoothpacket at the second time.
 3. The apparatus of claim 2, wherein theapparatus further comprises: means for avoiding transmission of thefirst Bluetooth packet at the second time in response to the second timebeing predicted to occur prior to the first time.
 4. The apparatus ofclaim 1, wherein the apparatus further comprises: means for notifying,in response to the second time being predicted to occur prior to thefirst time, a device to not transmit the wireless local area networkpacket prior to the transmission of the first Bluetooth packet.
 5. Theapparatus of claim 1, wherein the means for predicting the second timeis configured to predict the second time based on an assignment of slotsfor one or both of transmission and reception of Bluetooth packets. 6.The apparatus of claim 1, wherein the apparatus further comprises: meansfor issuing, in response to an end of the reception of both the wirelesslocal area network packet and the second Bluetooth packet, a receptionending synchronization signal.
 7. The apparatus of claim 6, wherein theapparatus further comprises: means for starting to transmit the firstBluetooth packet, subsequent to the issuance of the reception endingsynchronization signal.
 8. The apparatus of claim 1, wherein the meansfor predicting is configured to predict the first time at which thereception of the wireless local area network packet is going to end by:transmitting a power saving poll; in response to transmitting the powersaving poll, receiving a response, wherein the response includes anindication of a duration of time of the reception of the wireless localarea network packet; and based on the response, predicting the firsttime.
 9. The apparatus of claim 1, wherein the apparatus is includedwithin one of a laptop computer or a cell phone.
 10. A method fortransmitting wireless local area network packets and Bluetooth packets,wherein the method comprises: prior to transmission of a wireless localarea network packet, predicting a first time at which the transmissionof the wireless local area network packet is going to end, andpredicting a second time at which reception of a first Bluetooth packetis going to start; and in response to the first time being predicted tooccur prior to the second time, simultaneously transmitting the wirelesslocal area network packet and a second Bluetooth packet, wherein thefirst Bluetooth packet is to be received subsequent to the secondBluetooth packet being transmitted.
 11. The method of claim 10, furthercomprising: in response to the second time being predicted to occurprior to the first time, avoiding transmission of the wireless localarea network packet.
 12. The method of claim 10, further comprising:issuing a transmission ending synchronization signal in response to anend of the transmission of both the wireless local area network packetand the second Bluetooth packet.
 13. The method of claim 10, wherein themethod is executed by an apparatus that is included within one of alaptop computer or a cell phone.
 14. A method for receiving wirelesslocal area network packets and Bluetooth packets, the method comprising:prior to receiving a wireless local area network packet, predicting afirst time at which reception of the wireless local area network packetis going to end, and predicting a second time at which transmission of afirst Bluetooth packet is going to start; and in response to the firsttime being predicted to occur prior to the second time, simultaneouslyreceiving both the wireless local area network packet and a secondBluetooth packet, wherein the first Bluetooth packet is to betransmitted subsequent to the second Bluetooth packet being received.15. The method of claim 14, wherein predicting the first time at whichreception of the wireless local area network packet is going to endfurther comprises: transmitting a power saving poll; in response totransmitting the power saving poll, receiving a response, wherein theresponse includes an indication of a duration of time of reception ofthe wireless local area network packet; and based on the response,predicting the first time.
 16. The method of claim 14, furthercomprising: in response to the second time being predicted to occurprior to the first time, notifying a device to not transmit the wirelesslocal area network packet prior to the transmission of the firstBluetooth packet.
 17. The method of claim 14, wherein furthercomprising: in response to an end of the reception of both the wirelesslocal area network packet and the second Bluetooth packet, issuing areception ending synchronization signal.
 18. The method of claim 17,further comprising: subsequent to the issuance of the reception endingsynchronization signal, starting to transmit the first Bluetooth packet.